A number of promising technologies have emerged in the communications domain in recent years. The technologies include navigation with the aid of satellites and the conversion of mobile radio systems to mobile telephone systems, trunked radio and personal communications systems. The challenge is to make these technologies available in useable form.
These new systems themselves take a number of forms. For example there exists a geographically wide spread cellular network (for example, in Australia, there exists the Mobilenet (TM Telecom) administered by Telecom Australia). This network will hereafter be referred to as the cellular mobile telephone communication network.
Another of the new forms of mobile telephone is the trunked radio system which, in principle, operates along much the same lines as the cellular mobile telephone communication network to the extent that it comprises a series of radio transmitter/receiver stations distributed over a geographical area and interlinked in a manner whereby vehicle mounted or otherwise transportable corresponding radio transmitter/receiver units can communicate with (usually) the closest one of the distributed transmitter/receiver stations. All of the geographically distributed transmitter/receiver stations are interlinked so that communications across the network are effectively unified. The trunked radio system is utilised typically for specialised communication networks such as taxi communication networks or courier communication networks. Messages required to be sent over the trunked radio network are typically much shorter than those required to be sent over the cellular mobile telephone communication network and the trunked radio system is usually also tailored so that the cost of communication is less than for the cellular mobile telephone communication network.
Yet another form of the mobile telephone system is a personal communication system wherein the geographically distributed transmitter/receiver stations have only a limited range and for a mobile mounted or otherwise transportable transmitter/receiver to communicate with these stations requires that the transportable transmitter/receiver be within a specified distance of one of the distributed transmitter/receiver stations. These localised communication systems are frequently used in densely populated areas and require users to approach within a specified distance of easily identifiable transmitter/receiver stations before communication on the personal communication system can take place.